A practical treatise on variola ovina; or, Small-pox in sheep, containing the history of its recent introduction into England; with the progress, symptoms, and treatment of the disease; also the experiments instituted to ascertain its peculiar features, and the best means to avert its fatal consequences

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Preface

This Essay is based on a series of experiments which were instituted by the author in consequence of the sudden apappearance of a malignant exanthematous disease in the flocks of several agriculturists in the vicinity of London, and which seemingly depended on the sheep being mixed with some imported " merinos." An examination shewed that the malady possessed many of the features of human variola, and was, in fact, the small-pox of sheep.

Originally the author intended to have placed the matter before the veterinary profession in particular in a series of papers in the " Veterinary Record ;" but, finding that the disease rapidly extended, he resolved to bring his researches into its nature and treatment before the public in the form of a pamphlet. And he would fain indulge the hope that, in taking this course, he may be instrumental in benefitting the agricultural community, whose flocks are in danger of being decimated by a scourge which previously had confined its ravages to the continent. The work has been written during the intervals of professional avocations, combined with the delivery of a sessional course of instruction, and the author is well aware of its many imperfections ; yet he hopes it will be found to contain at least an outline of what is known on the subject. He could have wished that the task had devolved on one more capable of doing it justice ; but, considering the situation which he has the honour to hold, namely, the Lectureship on the Anatomy and Diseases of Cattle at the Royal Veterinary College, he felt that it was a duty from

PREFACE.

which he ought not to shrink. He has gleaned information from various sources, and has made free use of the labours of the continental pathologists, rather preferring to do this, in many instances, than to promulgate opinions of his own. In accomplishing his design, he trusts that he has rendered an acceptable service to his profession, and also one which will be deemed not altogether valueless by the practitioners of medical science. He is emboldened to make this latter remark, by observing that Dr. Gregory, Physician to the Small-pox Hospital, in his annual report, after narrating the particulars of the outbreak, and of the experiments, says that " the resemblance of this disease to small-pox is very remarkable, both in symptoms, mode of communication, and rate of mortality ;" and " when fully developed, the investigation can hardly fail to throw some new and valuable light on the history of small-pox, and on the relation which it bears to other diseases, both of man and animals."

In conclusion, the author has to acknowledge his obligations to many medical friends, among whom he wishes particularly to name, Mr. Ceely, Mr. Marson, and Mr. Erasmus Wilson; and he is equally indebted to his colleagues Professors Sewell, Spooner, and Morton, and also to Mr. Varnell, for assistance and advice in carrying out the investigations.

Royal Veterinary College, April 27, 1848.

Table Of Contents

CHAPTEE I.

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Small-pox of sheep, a new disease in England — Opinions of British authors on Ovine Variola — Antient writers on the diseases of cattle — General history of epizootic affections — Outbreaks of various malignant disorders among cattle and sheep — England visited by some of these scourges. Their supposed causes j.jg

Chapter I

Opinions of British Authors on Sheep-pox — Antient Writers on Diseases of Cattle — Epizootic Affections, including Sheep-pox — General History of these Maladies — Visitation of them in England — their supposed Causes.

The outbreak of a disease in any locality where it had hitherto been unobserved or unknown, except by name, cannot fail, whether man or animals be its victims, to excite the attention of the public ; but more especially must it receive attention from those persons whose avocation requires that they should investigate the causes which have led to its appearance, and make themselves conversant with its nature or character, and with the laws which govern its extension among that class of animals which seems most susceptible of its influence.

No surprise need, therefore, be felt at the interest which has been awakened by the appearance in this country of a disease attacking sheep, and having a strong resemblance to, if not identity with, that loathsome malady, the Small-Pox. This ovine disorder now bids fair to establish itself in England, and probably from time to time to break forth and decimate our flocks, as variola does, or used to do, our population*. Of late years both our cattle and sheep have suffered severely from epizootics, and we cannot but regret that the disease we are now treating of should be added to the number of these scourges ; for the interests not merely of the agriculturists, but of the whole community, must be seriously compromised if it is found to extend itself, as we have great reason to fear that it may do, since accounts are frequently reaching us of its having broken out in different and new places in the kingdom.

Variola Ovina is spoken of as a very destructive complaint in most parts of the continent, and several of those who have written on the subject, tell us that it frequently assumes the epizootic type ; many sheep probably being attacked during some seasons, and fewer in others. From the earliest periods down to the present time malignant diseases have raged on the continent, and some of them have visited England ; a question might, therefore, arise, has sheep-pox been one of the number ? To this it is, perhaps, impossible to give a decided negative ; but we incline to the opinion, that this malady has

* But a few years have elapsed since small- pox broke out with fearful violence in the city of Norwich, and carried off a large number of its inhabitants. Mr. Cross, writing of the affection, says : " It was comparatively dormant during the winter, and when the season became milder, it burst upon us suddenly and unexpectedly, continuing its work of devastation for three or four months with undiminishing fury." ' Upwards of 3000 persons, or a thirteenth part of the whole population were affected ; the total deaths were for the year [1819], 1352, and of these 530 died from small-pox, and 822 from all other causes.' — A History of the Variolous Epidemic, p. 4, 5, 8vo, London, 1820.

A NEW DISEASE IN ENGLAND 1 3

never till now existed here as an epizootic. To the best of our knowledge, no British author has described such a visitation, although several have handed down very full particulars relating to these epidemics. Mr. Youatt, in his work on Sheep (p. 541, 1837), speaking of ClaveUe, the French name for the affection, says " it never reached Great Britain, although it has thinned the sheep flocks in every district of France, opposite to the English coast." Mr. James Hogg, " the Ettrick Shepherd," makes no mention of sheep-pox from his own experience, but gives an account of it in a translation from the French of M. Vitet ; and it appears most probable that he was a stranger to the malady, for in a short article which precedes the translation alluded to, he observes, " that sundry of the diseases here treated of are analogous to those in our own country, consequently the cures must also be of use here ; and though others of them have not yet appeared in Britain, the introduction of foreign breeds may introduce foreign diseases. This we can neither guard too well against, nor be too well prepared for when it happens" (p. 191, Edinburgh, 1807). If, however, we turn to the pages of earlier authors on the disorders of cattle, we find mention made of a malady called sheep-pox ; but it must be borne in mind, that there is not much originality in their writings, which are often made up of translations from Italian and other Continental books.

Leonard Mascal, in his work on cattle, in the third book, where he treats of The Government of Sheep, makes these remarks : " Sheepe wil haue a scab, which shepheards call the pocks, and it wil appeare on the skin, like red pimples or purples, and they wil be broad

4 SMALL-FOX IN SHEEP.

like spots as broad as farthings, and there dieth many sheepe thereof, for lacke of looking too betimes. Therefore to handle often all your sheepe, and looke all ouer their bodies, and see if ye find any sheep taken therwith : ye shal by and by take him from his felows, and put him into some fresh pasture. And then see and looke daily to the rest of the flock, and draw them as ye shal see them infected therwith, and put them in fresh pastures if they haue it, in somer when there is no frostes, then it shalbe good to wash them in water. Remedies also. Some do take ye iuice of nightshade mixt with grease, and therwith anoint, or garlick beaten togither with tar, and so anoint. Or the iuice of pelitory of Spain, or of artichoke, mixt with strong vinegar, and therewith wash it. Other remedies shepheards haue the which I know not, but these I thinke shalbe sufficient," (4to, London, 1587, p. 231-2).

Ruscam, Gervase Markham, James Lambert, and others, who wrote shortly after Mascal, either copy his observations, or merely give their own recipes for the cure of the complaint. Ellis in his Sure Shepherd's Guide (page 324), speaking of the disorder, says, " My next neighbour had one [sheep] that came out in blotches from its horn to its mouth ; to cure it he made use of tar." The malady here indicated might be sheep-pox, or, what is more likely, an eruptive affection to which the ovine race are liable ; but arising from ordinary causes, as exposure to inclement weather, &c. Thus Virgil says,

" A scabby tetter on their pelts will stick, When the raw rain has pierced them to the quick."

Georgic III, Diyden's Translation, 1. 672.

A NEW DISEASE IN ENGLAND? 5

Ellis wrote in 1749, and since his time we find no mention made of this disease as affecting the sheep of this country : in fine, the only notice taken of it by English authors appears to arise from the introduction into their works of translations from foreign writers, as we have explained already. We, therefore, consider that the weight of evidence favours the opinion, that the outbreak of " variola ovina," which we are about to describe, depends on the importation of certain infected animals from abroad, and this will be greatly strengthened by a perusal of the facts which the sequel will disclose. Our insular position has, no doubt, protected us from many pestiferous affections that have proved destructive to cattle in France, Germany, Italy, and other Continental states ; epidemics in which contact is absolutely necessary to convey the disease ; for although several of these maladies are both infectious and contagious, we must remember that they are only so within a given distance, this is probably the case with variola ovina.

We shall now proceed to take a brief view of these pestilential scourges, which we are the more desirous of doing, because some of them appear to have points in common with the malady here treated of.

The most ancient records of both Scriptural and Pagan history make frequent mention of such epidemics ; and, in the time of Moses, we first learn that Egypt had her cattle swept off by what was called " murrain," a term, perhaps, employed to designate a class of diseases. The cause of this dreadful visitation was the disobedience of Pharaoh to God's commands, in detaining the children of Israel ; and, it is related, that all kinds of animals fell victims to the scourge. " The Lord did that thing on the morrow, and all the cattle in Egypt died." Are we to look upon this as a Divine punishment, employed on a specific occasion, and to cease for ever afterwards ? Or, rather, may we not consider that here was a beginning of certain diseases which, governed by particular laws, were destined, from time to time, to lay low the flocks and herds of other nations, sparing not even man himself? However much the origin or causes of these maladies may be beyond our ken, we have positive proof of their effects ; and, since the period referred to in the Bible, epizootic disorders have been so frequent, as to attract the attention of historians in all countries. To the early poets of Greece and Rome we are indebted for accounts of some of these visitations ; frequent allusions being made to them in the writings of Homer, who flourished about 900 years before the Christian era. Virgil and Ovid also furnish graphic descriptions of them.

Virgil thus writes,

" On winter seas we fewer storms behold Than foul diseases that infect the fold. Nor do these ills on single bodies prey, But oft'ner bring the nation to decay, And sweep the present stock and future hope away.

A dire example of this truth appears, When, after such a length of rolling years. We see the naked Alps, and their remains Of scattered cots and yet unpeopled plains, Once fill'd with grazing flocks, the shepherd's happy reigns.

Here, from the vicious air and sickly skies A plague did on the dumb creation rise :

EPIZOOTICS IN ANCIENT TIMES. 7

During the autumnal heats the infection grew, Tame cattle and the beasts of nature slew ;

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Sheep, oxen, horses fell, and, heaped on high, The diff'ring species in confusion lie*.''

Such is a poetical account of one of these epizootics, as it raged among the Alps, probably not less than 2000 years since. We also learn from Plutarch that, in the days of Romulus, or about the time that Rome was founded (750 B.C.), a great plague, after destroying the fruits of the earth and the cattle, swept off many of the people. And Livy says, " The consuls had the greater difficulty to raise their recruits, because the plague, which the year before had raged among horned cattle, broke out among men." We find, however, that Varro and others, the earliest writers on husbandry, are nearly silent on these affections. Columella, the author of one of the most valuable works on Roman agriculture, and who flourished shortly after the birth of Christ, views them as contagious disorders, and has handed down some instructions for their cure. It is not until the fourth century, when they are again mentioned by Vegetius, that we have much further information about them. This veterinary writer, after describing several varieties of " the distemper or plague," goes on to observe : — " All these diseases are full of contagion, and if they seize an animal, they pass immediately to all ; and so they bring destruction sometimes either upon whole herds, or upon all those that are tame and broke for labour. Therefore the animals which have been once attacked, must, with all diligence and care, be separated from the herd, and put apart by themselves, and sent to * Gboroic 3, 1. 711 — 829, Dryden's translation.

those places where no animal is pastured, lest, by their contagion, they endanger all the rest, and what results from the negligence of the owner be imputed, as is usually done by fools, to the Divine displeasure*." Cardinal Baronius states, that in the year 376, when the cattle died of the plague all over Europe, none escaped but such as were marked on the forehead with the sign of the cross, by which miraculous immunity many persons are said to have been converted to the Christian faith.

In the year 810, it is stated that an epizootic raged to such an extent as to destroy every head of cattle in the Emperor Charlemagne's army, and to have been fearfully destructive throughout the German empire. It would be useless at present to attempt to trace the history of epidemics in the dark ages.

In the sixteenth century, however, various outbreaks are related of malignant affections among cattle ; and Rammazini records that the Venetian states suffered greatly in 1514 and 1599, when "all beef and veal, and likewise milk, were forbidden by the senate to be eaten." He also says, that at Modena, in 1690, the season was cold and moist ; and the distemper of that year attacked all the people who lived in the country, and spread indiscriminately among all kinds of animals, killing great numbers after a few days' illness. Nature made strong efforts to disengage herself from the disease. A critical discharge manifested itself on the thighs, neck, and head, resembling the pustules of small-pox. Most of the animals which had this appearance, lost their eyesight. Those creatures which were not carried off by the disease, but resisted its first vio-

* Translation of Vegetius Renatus on Diseases of Horses and Oxen. London, 8vo, 1748, p. 227-8.

EPIZOOTICS IN THE XVII CENTURY. 9

lence, lost their flesh by degrees, and fell into a marasmus.

Rammazini did not scruple to declare these pustules to be the small-pox ; for they differed not from it in form, in colour, or in the manner in which they went off: when they had dried off after the suppuration, they left a black scar, like that which remains after the small-pox. This epidemic contagion continued in 1691, and attacked chiefly the sheep, so violently that the breed was almost destroyed. It has been constantly observed, that of all animals sheep are the most subject to small-pox. It was, therefore, to be expected that they should be particularly affected with it, since they are more disposed to it than other cattle*."

In 1693 pulmonary phthisis proved very destructive to oxen, and " Hesse saw her herds carried off by it :" the supposed cause being the changeable condition of the atmosphere.

Lower Hungary is said to have suffered severely in 1 7 1 2, at the early part of the year, from a malady attacking the cattle which is not very clearly described ; but in August of the same year we learn " that a new kind of disorder shewed itself, associated with white pustules filled with matter insufferably stinking." And Mills adds 1 , that " every circumstance, especially the pustules, declare this distemper to have been the small-pox, complicated with some other disease. The liquor which flowed from the mouth greatly resembled the spitting which comes on in men in the small-pox. The difficulty of breathing, the stench of the breath, and the infectious smell of the pustules, are symptoms which constantly attend the clavin, claveau, or small-pox in sheep."

* Mills on Cattle, London, 8vo, 1776, p. 407-8. C

Of late years the progress of these distempers has been regularly traced in Europe ; and the one from which the cattle of Italy, Germany, France, Holland, and Great Britain, suffered in 1711-12, came from Hungary, being imported by some oxen into the neighbourhood of Padua. The infection seems to have been communicated by the saliva, for, say the historians, " when this is dropped on the grass, and sound animals are immediately placed on the same pasture, they contract the disorder, and in some bullocks the tongue was inflamed and covered with many red blisters." From this description it would appear that the malady resembled the one now existing in this country, and to which we have given the name of Eczema Epizootka.

In 1713 Rome and its neighbourhood suffered greatly from the same epizootic. The prophylactic measures had recourse toby Pope Clement XI are said, by Lancisi, to have preserved, for two years, the cattle in the Ecclesiastical dominions ; but the disease was then introduced. It is recorded that orders were issued to suppress a fair about to be held at Frusino, a town bordering on the kingdom of Naples, and that the drovers, being thus prevented from disposing of their oxen, took them by circuitous roads to Rome, where they sold them at a low price. This circumstance also facilitated the disposal of many of the cattle to various persons residing in the villages through which they passed, and thus the affection spread through the Papal states, and killed nearly thirty thousand animals in the succeeding nine months ; a register having been kept from October 1713 to April 1714, when the malady is stated to have ceased.

EPIZOOTICS IN THE XVIII CENTURY. 11

In 1730, Bohemia, Saxony, and the Duchy of Magdeburg, were visited by a similar pestilence, the first symptom of which is described to be " a white blister that appeared on the tongue of the affected animals."

In 1745 the cattle of Italy, France, Germany, and England were destroyed by thousands ; and it is worthy of observation, that this disease seems to have been very analagous to, if not identical with, pleuro-pneumonia. By some authors it is said to have been brought from Holland by certain calves imported into the vicinity of London by a farmer for the purpose of crossing the breed ; while others assert that the lucrative views of an English tanner, who bought a parcel of distempered hides in Zealand which were forbidden to be sold, was the origin of the affection.

A very good account of the malady has been left to us by Dr. Barker, who in his description of the post-mortem appearances, says, " I have constantly found the bloodvessels of the lungs stuffed up, and distended with grumous or coagulated blood, and the bronchia or air-vessels so much inflated as to make the bulk of the lungs appear much larger than usual. And though some of these cattle were opened before the body was cold, or the blood congealed in the other vessels, yet in those of the lungs it was constantly found to be coagulated to such a degree, as not to flow out of the vessels upon cutting them*."

We have already made mention of an affection described by Ptammazini to be the small-pox, which committed fearful ravages among the sheep at Modena

* An account of the present epidemical distemper amongst Black Cattle (London, 1745.)

in 1690. We have again to record another outbreak of that disease in 1746, which continued with more or less severity in Picardy till 1792. " The sheep were affected with a contagious malady which the French commonly call clav'm or claveau, and which is, in fact, no other than the small-pox. It is, of all the contagious distempers which affect sheep, the most easily communicated, and that to which they are the most liable. Like the small-pox, too, it is distinguished into the distinct or mild, the confluent or malignant*."

In the interval between the above dates, that is, about 1758, another of these epizootics reached our shores, and many of our cattle died. Dr. Layard describes it as a putrid, malignant, and inflammatory fever, attacking the ox tribe, and producing ulcers in the mucous membranes and external parts of the body ; and says that he had often seen sheep, pigs, horses, and dogs in the midst of the infectious without being contaminated by it.

In 1763-4 our cattle again fell victims to one of these diseases : the digestive organs were the chief seat of the affection, and parasites were present, viz. intestinal worms, and flukes in the liver. Sheep suffered severely. This disorder seems, however, to have been no other than " the rot."

From this period down to 1838-9 England seems to have escaped ; but suddenly in the former year an epizootic associated with fever, and with vesicles on the tongue, lips, teats, and between the digits, made its appearance among our cattle, attacking oxen, sheep,

* Mills on Cattle, p. 420.

CAUSKS OF KPIZOOTICS. 13

and pigs ; even poultry were similarly affected. This disease would appear to be like that which existed in Saxony in 1730, and probably also in this country in 1711-12 : it is too well known to need any particular description. We regret to say that it still continues in the British Islands, and has produced great losses to the owners of stock, although it is rarely now found to prove fatal. That destructive malady pleuro-pneumonia followed closely upon it.

The latest of these epizootics is the especial object of this treatise, viz. the small-pox among sheep.

Having thus given a condensed history of pestilential affections, which clearly shews that the " Clavalee" has not been among those that have broken out among our flocks and herds, we will now offer a few remarks on the supposed causes of these maladies.

Exposure to the changeable state of the weather, the partaking of bad provender or stagnant water, are viewed by many as the chief causes of epidemics, while others trace them to a vitiated condition of the atmosphere ; but whether such state consists of a mingling of mephitic vapours or deleterious gases arising from either animal or vegetable decomposition, or from an excess of humidity or dryness affecting the electrical condition of the air, they scarcely venture to conjecture. That the gaseous compounds eliminated from decomposed animal substances are highly injurious to health, cannot be doubted, although these may not singly originate epidemics ; hence one reason of burning or burying the dead. It is, indeed, much to be wished, that all putrescent matters were removed as far as possible from places where they are likely to be injurious to public health.

Virgil, in his description of the causes and effects of an epizootic thus expresses himself,

" At length whole herds to death at once it sweeps ; High in the stalls it piles the loathsome heaps ; Dire spectacle ! till sage experience found To bury deep the carrion in the ground. Useless their hides, nor from the flesh the flame Could purge the filth, nor steams the savour tame."

Georgic, lib. Ill, v. 556. Wharton's translation.

In the days of Homer the effects were attributed to the offended gods ; but whether his account is, or is not, symbolical of a vitiated air, we cannot determine. Tbe antiquity of such an opinion is clearly shewn by the extracts we have made from Virgil. Ovid also viewed the atmosphere as the chief cause, and, when speaking of the destruction of the island of iEgina, he observes,

" With deadly blasts the fatal south wind blew, Infected all the air, and poisoned as it flew.

********

The tabid sheep with sickly bleatings pines, Its wool fast wasting as its strength declines."

Livy, too, in his account of a pestilence in his time, imputes it to the air.

Pliny, who wrote a few years afterwards, affirms that these opinions were not general, and that the quality of the food was considered dangerous, more especially the " rust of grass." He speaks of the disease as an effect of God's wrath, and observes that Numa Pompilius, the successor of Romulus, instituted festivals called Rubigalia Festa, to avert its consequences : these were celebrated in April, because the rust usually began in that month.

COMMUNICATION OF EPIZOOTICS. 15

In the present state of science we are compelled to admit that the causes of epidemic affections are as little understood as they were centuries since ; and although a strict attention to diet, and protection from the vicissitudes of weather, will go far to render animals insusceptible to diseases in general, it must, nevertheless, be admitted,,that these means, valuable as they are, do not give absolute immunity from such attacks.

Whatever the combination of causes may be which produces these maladies, certain it is that very many of them assume an infectious nature, otherwise we could not account for animals separated and kept apart from those which are diseased, frequently and sometimes altogether escaping, while those are sure to become early victims that are allowed to pasture or live with the affected ; besides, we can often succeed in producing the malady by inoculating healthy cattle, thus shewing how closely the spread oft the disorder depends upon contagion or infection. The fact, however, of animals when in health, if placed with affected ones, contracting a disease of the same kind as that which the latter are suffering from, is the best proof of the infectious or contagious nature of a complaint. An animal escaping an attack, when such affections are raging in the locality in which it is placed, may arise from a variety of causes, as non-susceptibility, and also the possibility of the exciting agents never having been brought within its sphere of inhalation. For although each victim to a destructive epidemic may be considered as adding new seeds or fresh energy to the malady by the exhalations arising from its body, we must not lose sight of the circumstance, that very many infectious diseases assume an endemic type, whilst others which are spread over a vast extent of country are often observed to take a particular direction. There are, however, diseases of this kind that appear to be guided by no determined rules, breaking out again and again in the same neighbourhood ; but even here we may suppose, with good reason, that the deleterious atmosphere floats, as it were, in nebula, and is driven hither and thither by the currents, sacrificing fresh subjects placed in the course of its passage.

Although, then, " one swallow does not make a summer," yet one positive proof of the communication of disease from animal to animal should render us very cautious, and much influence the opinions we may give on so important a point.

Judging from our present experience and observation, as well as from the facts related to us, we have every reason to fear that Variola Ovina is both contagious and infectious.